1. Field of the Invention
The present invention relates to an ink jet recording apparatus and particularly to such an ink jet recording apparatus in which ink is supplied from a plurality of stationary ink tanks to a recording head mounted on a movable carriage, via a plurality of ink supply tubes, respectively.
2. Discussion of Related Art
Patent Document 1 (Japanese Patent Application Publication P2002-240310A) or Patent Document 2 (Japanese Patent Application Publication P2000-309109A) discloses a tube-supply-type ink jet printer including a plurality of recording heads having a plurality of arrays of nozzles, respectively, that eject, for recording a full-color image, a plurality of color inks, respectively, such as a black ink (BK), a cyan ink (C), a yellow ink (Y), and a magenta ink (M); a plurality of buffer tanks that accommodate respective amounts of the corresponding color inks, and air bubbles; a movable carriage that is movable relative to a housing and on which the recording heads and the buffer tanks are mounted; a plurality of stationary ink tanks that store the color inks, respectively, and are disposed in the housing; and a plurality of flexible ink supply tubes that supply the color inks from the ink tanks to the buffer tanks, respectively.
In the above-indicated conventional ink jet printer, air in the atmosphere dissolves little by little into the color inks through respective walls of the ink supply tubes, and the air dissolving in the color inks develops little by little into air bubbles in the ink supply tubes and/or the buffer tanks. Therefore, each of the buffer tanks collects the air bubbles in an upper portion thereof so as to prevent the air bubbles from entering a corresponding one of the recording heads. When respective pre-set amounts of air bubbles are collected in the buffer tanks, an air discharging pump is operated to discharge the air bubbles from the buffer tanks via respective air discharging passages that are connected to the respective upper portions of the buffer tanks.
Meanwhile, if, when an ink jet recording apparatus is shipped from a factory, a plurality of ink flow channels including a plurality of ink supply tubes, a plurality of buffer tanks, and a plurality of recording heads, respectively, are full of air, air bubbles may be left in the ink flow channels of the new ink jet recording apparatus when a user initially fills those channels with a plurality of color inks, respectively. Thus, the new apparatus may fail to eject the inks. To prevent this problem, it is usually practiced to fill, before the ink jet recording apparatus is shipped from the factory, each of the ink flow channels with a maintenance liquid (e.g., a liquid having a basically same composition as that of an ink but not containing a coloring agent) and liquid-tightly seal, with a sealing member, a free end of a corresponding one of the ink supply tubes that is to be connected to a corresponding one of a plurality of ink tanks.
Thus, when the user purchases the new ink jet recording apparatus and starts using the apparatus, i.e., initially introduces the apparatus, the user needs to connect, according to a user's manual, the respective free ends of the ink supply tubes to the corresponding ink tanks, then move a maintenance unit, provided at a waiting position in the housing, so as to contact closely respective nozzle supporting surfaces of the recording heads, and operate the maintenance unit to discharge the maintenance liquid from the ink flow channels and fill those channels with the color inks supplied from the ink tanks. However, this method suffers such a problem that small ink flow passages provided in the recording heads exhibit a great resistance to flow of the maintenance liquid and accordingly the color inks cannot be quickly supplied from the ink tanks to the ink flow channels including the buffer tanks.